Samuel l



(No Model.) S. L. BARRIETT.

AUTOMATIC SWITCH FOR ELECTRICAL APPARATUS.

No. 595,803. Patented De0.21,1897.

WITNESS INVENTOR M A TTOR/VE) UNITED STATES PATENT OFFICE.

SAMUEL L. BARRIETT, OF NEW YORK, N. Y.

AUTOMATIC SWITCH FOR ELECTRICAL APPARATUS.

SPECIFICATION formingpart of Letters Patent No. 595,803, dated December21, 1897.

Applicatlonfiletl September 9, 1897. Serial No. 651,154. (No model.)

To all whom it may concern.-

Be it known that I, SAMUEL L.-BARRIETT, a citizen of the United States,residing in New York, in the county of New York and State of New York,have invented certain new and useful Improvements in an Automatic Switchfor Electrical Apparatus; and I do declare the following to be afull,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

My invention relates to an improvement in automatic cut-out devices asapplied to rheostats, starting-boxes, or other switching apparatus usedfor electrical purposes; and the object of my invention is to provide adevice or arrangement by which the lever, arm, or contact-maker of suchswitching apparatus is made to automatically return to a given or fixedposition (from whatever position it may formerly have occupied) eitherby reason of an excessive flow of current or when the circuit is by anymeans broken. In the first instance the device serves as a safeguardagainst overload currents and short circuits, and in the second instanceit provides that the circuit shall remain open until it is desired bythe operator to again close it. This latter qualification is importantfor the reason that should the current momentarily cease it cannot startup again suddenly to the probable detriment of the electrical devices inthe circuit.

I shall explain and describe my invention as applied to a rheostat orstarting-box to be used in connection with electric motors. In formerdevices of this class the lever, arm, or contaet-maker is moved from theposition of no current or open circuit over a series of contactpoints,decreasing the resistance in the circuit as the arm is moved forwardover the successive contact-points until the resistance of the rheostatis all out and the motor is supplied with the full pressure. In thisfinal position the lever, arm, or contact-maker is held (against thepull of a spring toward open circuit) by a suitable catch, dependingupon the action of an electromagnet.

A feature of my invention resides in the fact that the lever, arm, orcontact-maker will return to its position of open circuit from anyposition that it may have occupied previous to the excessive flow orcessation of flow of current.

Referring to the drawings, Figure 1 shows a View looking down on top ofthe startingbox, and Fig. 2 shows a front elevation.

10 and 10 are the main terminals of the instrument and serve to connectit in series with the armature of the motor. The current passes from theleft-hand terminal 10 through the coils of the electromagnet 4, (woundwith coarse wire,) thence to the contact-plate 9, through thecontact-spring 8 and arm 2 to the terminals of the resistance-coils, andso to the right-hand terminal 10. The electromagnet 3 (wound with finewire) is connected in series with the field-coils of the motor by meansof the terminals 1.1 and 11. The arm 2 carries the circular arc of softiron 1, which acts as a keeper or armature to the magnet 3. One end ofthis armature is fastened to the arm 2 at 7, while the other end issupported by the piece 6, fastened to the pole of the magnet 3 in suchmanner that the armature 1 is compelled to slide close to both poles ofthe magnet, which are shaped to fit it, as

shown.

The action of the instrument is as follows: The magnet 23, being inseries with the fieldcoils of the motor, becomes energized when themain-line switch is closed. It therefore attracts the armature 1 andholds it with such force against its poles that as the arm 2 is movedover successive contact-points the torque of the coiled spring 16,tending to return the arm 2 to the position of open armature-circuit, isovercome. The result is at whatever position it is desired to have thearm 2 the magnet 3, acting through the armature 1, will maintain it inthat position. If, however, the circuit by any means is broken, themagnet 3 loses its energy and the armature 1 ceases to be attracted.Therefore the coiled spring 16 quickly returns the arm 2 to the positionof open circuit. Again, shouldzthe flow of current become too great theelectromagnet 4 will become sufiiciently energized to draw up itsarmature 13 against the force of gravity. \Vhen this happens, theterminals 11 and 11 of the magnet 3 are connected together by means ofthe contacts 11 and 11 and the armature 13. This shortcircuits themagnet 3, which thereupon becomes demagnetized, allowing the armature 1to slip past its poles and the arm 2 to open the circuit. The criticalexcess of current is provided for by adjusting the lock-nuts 14 in anobvious manner.

The foregoing description shows the invention as applied to an ordinaryrheostat or starting-box; but the invention is designed to be used withany electrical apparatus where it is desired to maintain any particularpart lever arm, or contact-switchin any position and to automaticallyreturn the same to a given or fixed position.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is-

1. In a switch for electric apparatus in combination with an arm movingover successive contact-points, and an electromagnet having a curvedsegmental band-armature, which acts to maintain said arm in contact withany one of said contact-points against the action or force tending toreturn the arm to off position, substantially as described.

2. In a switch for electric apparatus in combination with an arm movingover successive contact-points and a magnet having a curved segmentalband-trniature holding the arm upon any one of said contact-points,means for automatically releasing and returning said arm upon anabnormal flow of current allowing the arm to return from any position tooff position, substantially as described.

3. In aswitch for electric apparatus in combination with amovable arm, asegmental bandarmature, suitable means for holding the arm in anydesired position, a mechanism to short-circuit theretaining-clectromagnct upon an excessive flow of current, a mechanismadapted to release the arm upon a cessation of a fiow of current,allowing the arm to return to the off position, substantially asdescribed.

In testimony whereof I affix my signature in presence of two witnesses.

SAMUEL Ii. I-EARIHICT'I.

Witnesses:

CHAS. CONARD. JOHN MARE.

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